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Diffusion-Ordered Spectroscopy for Rapid and Facile Determination of Consumer Plastic Molecular Weight
Analytical Chemistry ( IF 6.7 ) Pub Date : 2023-05-25 , DOI: 10.1021/acs.analchem.3c00655 Taylor F Nelson 1 , Collin P Ward 1
Analytical Chemistry ( IF 6.7 ) Pub Date : 2023-05-25 , DOI: 10.1021/acs.analchem.3c00655 Taylor F Nelson 1 , Collin P Ward 1
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Molecular weight (MW) is a key control of plastic polymer properties and their fate in the environment. However, the primary tool used to determine plastic MW, gel permeation chromatography (GPC), has major limitations, such as low precision and accuracy, requirements for dedicated instrumentation, production of high volumes of hazardous waste, and large sample sizes. In this study, we describe, validate, and apply a diffusion-ordered spectroscopy (DOSY) method for polymer MW determinations, with a focus on applications for consumer plastics. Several experimental conditions were systematically optimized and tested to validate the DOSY method, including the selection of pulse sequences, the effect of sample concentration, cross-validation with multiple sets of external standards, and long-term instrumental stability. Validation was performed for a wide range of polymers, solvents, and temperatures, highlighting its potential for broad applicability. A preliminary screening of polystyrene and polyethylene terephthalate consumer products revealed widely varying MWs (up to two-fold) for products made of the same polymer type. A preliminary experiment was also conducted to track the decrease in polystyrene MW via photochemical chain scission reactions, finding a 20% reduction in MW after less than 1 week of irradiation. Collectively, our results demonstrate the potential for DOSY to provide high-throughput, accurate, and precise measures of polymer MW, as well as the evolution of polymer MW during environmental weathering processes, such as photochemical degradation. We conclude with a discussion of (i) the many advantages of DOSY compared to GPC, (ii) future developments to enhance the depth of information obtained from DOSY, and (iii) approaches to broaden the accessibility of this promising analytical method to the research community.
中文翻译：
用于快速简便地测定消费塑料分子量的扩散有序光谱法
分子量 (MW) 是塑料聚合物特性及其在环境中命运的关键控制因素。然而，用于确定塑料 MW 的主要工具凝胶渗透色谱 (GPC) 具有重大局限性，例如精度和准确度低、需要专用仪器、产生大量危险废物以及样品量大。在这项研究中，我们描述、验证和应用扩散有序光谱 (DOSY) 方法测定聚合物分子量，重点是消费塑料的应用。系统地优化和测试了几个实验条件以验证 DOSY 方法，包括脉冲序列的选择、样品浓度的影响、与多组外部标准的交叉验证以及长期仪器稳定性。对各种聚合物、溶剂和温度进行了验证，突出了其广泛适用性的潜力。对聚苯乙烯和聚对苯二甲酸乙二醇酯消费品的初步筛选显示，由相同聚合物类型制成的产品的分子量差异很大（高达两倍）。还进行了一项初步实验，以通过光化学断链反应追踪聚苯乙烯 MW 的降低，发现在不到 1 周的照射后 MW 降低了 20%。总的来说，我们的结果表明 DOSY 有潜力提供高通量、准确和精确的聚合物 MW 测量，以及聚合物 MW 在环境风化过程（如光化学降解）中的演变。我们最后讨论了 (i) DOSY 与 GPC 相比的许多优点，
更新日期：2023-05-25
中文翻译：
用于快速简便地测定消费塑料分子量的扩散有序光谱法
分子量 (MW) 是塑料聚合物特性及其在环境中命运的关键控制因素。然而，用于确定塑料 MW 的主要工具凝胶渗透色谱 (GPC) 具有重大局限性，例如精度和准确度低、需要专用仪器、产生大量危险废物以及样品量大。在这项研究中，我们描述、验证和应用扩散有序光谱 (DOSY) 方法测定聚合物分子量，重点是消费塑料的应用。系统地优化和测试了几个实验条件以验证 DOSY 方法，包括脉冲序列的选择、样品浓度的影响、与多组外部标准的交叉验证以及长期仪器稳定性。对各种聚合物、溶剂和温度进行了验证，突出了其广泛适用性的潜力。对聚苯乙烯和聚对苯二甲酸乙二醇酯消费品的初步筛选显示，由相同聚合物类型制成的产品的分子量差异很大（高达两倍）。还进行了一项初步实验，以通过光化学断链反应追踪聚苯乙烯 MW 的降低，发现在不到 1 周的照射后 MW 降低了 20%。总的来说，我们的结果表明 DOSY 有潜力提供高通量、准确和精确的聚合物 MW 测量，以及聚合物 MW 在环境风化过程（如光化学降解）中的演变。我们最后讨论了 (i) DOSY 与 GPC 相比的许多优点，
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